Respuesta :
When we say essential appositive, this is the phrase that is considered as an important part of the sentence that describes the noun and cannot be omitted for this will change the thought of the sentence. Based on the given sentence above, the essential appositive would be "Famed Astronomer". The answer would be the first option.
The answer is Galileo because it is important to add this information rather than to just say "Famed astronomer".